Assisted Hatching (AH)

The zona pellucida (ZP) of mammalian eggs ang embryos is an acellular matrix composed of sulfated glycoproteins with different roles during fertilization and embryo development.

One of the dilemma in IVF is the failure of implantation after the transfer of normal-looking embryos into the uterine cavity. This failure may be due to an intrinsic embryo abnormality or defective uterine receptivity or hatching failure.  Assisted hatching (AH) is aimed to overcome the problem of hatching and is indicated in :

• Patient > 37 years of age

• Patient with high day 3 basal FSH

• Patient with embryo’s zona pellucida thickness > 15 µm

• Patient with > 2 previous IVF failures

• Patient undergoing frozen / thawed embryo transfer

Currently, these are 5 methods to perform AH

• Mechanical method by the use of a PZD needle

• Zona drilling through the use of acid Tyrode’s solution

• Laser techniques : The size of hole is precise and related to the laser exposure time and thus the system is simple,  easy, quick , very precise , chemical free and less mechanically invasive.

• Piezzo technology to cut through the zona

• Biochemical digestion of the zona using protease enzyme.

Jetanin ‘s criteria for AH (by  Laser) :  zona pellucida thickness > 15 µm and/or cryopreserved embryos.

 

Reference

1. Anna Veiga, Irene Boiso . Assisted hatching. Text book of Assisted Reproductive Techniques ( Laboratory and Clinical Perspective) 2001; 159-167

2. Teraporn Vutyavanich M.D. , M.Med.Sci. , Wirawit Piyamongkol M.D.,Ph.D. and Warunya Ittipunkul B.Sc. ; Assisted Hatching and Preimplantation Genetic Diagnosis . Color Atlas of Human Gametes and Embryos 2006 ;  86-90